Web edition: February 28, 2006
Print edition: March 4, 2006; Vol.169 #9 (p. 143)

Impure thoughts

Epidemiologist Scott Davis warns, "Melatonin supplements are not regulated" the way drugs are. ... "There may be all kinds of impurities and contaminants" ("Bright Lights, Big Cancer: Melatonin-depleted blood spurs tumor growth," SN: 1/7/06, p. 8). Are you really going to tell me that you aren't going to take melatonin—if you're convinced that it might lower your chance of getting cancer by as much as 50 percent—because you are afraid of impurities?

James Street
Oakland, Calif.

Daydream on

It seems to me irresponsible even to float the idea, as neurologist David M. Holtzman does, of chemically suppressing idle thought and daydreaming in people ("Alzheimer Clue: Busy brain connections may have downside," SN: 1/7/06, p. 3). Who can claim a basis for clinical discrimination of "bad" idle thought and daydreaming from the "idle thought" of intuitive problem solving and poetic imagination? More of human existence is at issue than the scourge of Alzheimer's.

Dennis Schmidt
Falmouth, Mass.

In the article, scientists drew the conclusion that busy brain connections may have the downside of producing "amyloid beta, the waxy protein implicated in Alzheimer's disease." I don't see why the following conclusion wasn't reached: Idle brains may have a downside. In the described study, it was lack of directed thought, not busy, directed thought, that seemed to use the same areas of the brain involved in Alzheimer's disease. Other studies show that people who use their brains actively seem to be protected from the disease.

Elizabeth Oscanyan
Philomont, Va.

Print addition

"Stone Age Footwork: Ancient human prints turn up down under" (SN: 1/7/06, p. 3) brought a strange conundrum to mind. If Paleolithic man was in Australia 40,000 years ago, why were the aboriginal people still living in the Stone Age when the first Europeans arrived? There were advanced cultures in the Americas by 100 B.C.E., whose ancestors had arrived by 12,000 to 15,000 years ago.

Norbert Edwards
Buffalo, N.Y.

Why modern civilizations appeared where they did remains unclear. Aboriginal cultures were every bit as complex as those elsewhere and adapted to an incredibly harsh environment.—B. Bower